//
// Created by 下次一定 on 2021/9/3.
//

/*开平方*/


#include <iostream>
using namespace std;

int n;

int main(){
    scanf("%d",&n);

    double l=0,r=n;
    //比有效值多2
    while(r - l > 1e-8){
        double mid =(l+r)/2;
        if(mid * mid>=n) r=mid;
        else l=mid;
    }
    cout<<l;


}